Direct coronary artery revascularization on a beating heart was conducted, both experimentally and clinically, in the 1950's and the 1960's, without stabilization. Challenges associated with this surgical technique are as follows:                complete anastomosis is very difficult to achieve due to the motion of the beating heart;        the technique is limited to vessels of a minimum diameter—again due to difficulty in the anastomosis technique on a beating heart;        lifting of the heart for revascularization of posterior arteries results in a precipitous drop in arterial pressure;        the learning curve for surgeons performing this technique is very high; negotiating the learning curve may represent significant surgical morbidity and mortality.        
The development of the cardio-pulmonary machine for extracorporeal circulation (ECC) enables coronary operations on an arrested heart. This allows the surgeon to operate on a perfectly still heart and to manipulate the heart to expose the target artery.
At the present time, the standard coronary artery bypass graft (CABG) procedure typically requires a full median sternotomy and extracorporeal circulation through a cardio-pulmonary machine.
Even with the constant technological improvements achieved during the last twenty-five years, the advantages offered with ECC have been offset by morbidity and mortality related to the ECC itself. The inflammatory response, as well as systemic microembolisms generated by ECC, induce to some extent a dysfunctional state of the brain, lungs and kidneys, which tends to increase with the aging of the patient. Furthermore, evidence suggests that when ECC can be avoided, the left venticular function is better preserved, thereby reducing risk of postoperative complications.
As a result, alternate CABG procedures that do not rely on the use of ECC offer distinct advantages.
Recently, minimally invasive surgery, involving a partial sternotomy or mini-thorocotomy, has generated much interest since it removes precisely the need for ECC. This surgery does, however, have its limitations. It is adequate for only one or two coronary bypass grafts. Moreover, it does not provide access to the posterior descending or circumflex arteries, and impairs both the anastomosis and the surgeon's vision due to the limited heart exposure.
These limitations may lead to future, more-invasive surgical interventions through partial or full sternotomy, if “blockages” progress in those arteries which were not accessible via minimally invasive procedures.
Therefore, partial revascularization may lead to re-intervention which not only represents a disadvantage to the patient but a financial burden to the health care system.